(a) Field of the Invention
The present invention relates to a display device for vehicles, aircrafts or the like. More particularly, the present invention relates to a movable display device which allows the installation position of display means and the angle of a display surface to be varied depending on the driving condition of a vehicle.
(b) Background Art
A display device for a vehicle serves to inform a driver of vehicle conditions that are important for driving the vehicle, such as, but not limited to, vehicle velocity, vehicle driving distance, the amount of fuel available, revolution per minute (rpm) of the engine, the temperature of cooling water, warning indication, etc.
Accordingly, the driver operates a vehicle while checking various circumstances such as, but not limited to, other vehicles, obstacles, traffic lights, traffic signs and so forth at the outside of a vehicle body with his or her naked eyes, and also simultaneously perceives the vehicle situations displayed on display means mounted at the interior of the vehicle.
FIG. 8 is a schematic diagram showing a sight line moving angle between a sight line connecting a driver's eye to display means and a sight line connecting the driver's eye to a target when viewed from a side of the vehicle wherein the right of the drawing is the advance direction of the vehicle.
Conventionally, a display means 4 is often embedded at a side of a dashboard in front of a driver (hereinafter, referred to as ‘initial position 41a’). When a vehicle drives at a relatively low speed, the driver's 30 sight generally remains at a position close to the vehicle. Thus, the fact that the display means 4 is positioned at the initial position 41a does not matter. In certain cases, when the vehicle drives at a high speed, the driver's sight is generally fixed to a target that is located far from the driver's vehicle. Thus, a sight angle to the target, namely a sight line 31 from the driver's eye 31 to the target substantially closes to a horizontal line. Thus, a sight line moving angle 33 between a sight line 32 from the driver's eye 31 to the display means 4 and a sight line 31 from the driver's eye 31 to the target is suitably increased.
Even though displayed information, which the driver frequently checks, is varied depending on respective driving situations, the conventional instrument panel merely displays preconfigured information. Such preconfigured display is not suitable for effectively reflecting a current driving situation.
Accordingly, if there is an increase in the time taken for a driver 30 to revert his or her eyes to the display means 4 from the front of the vehicle body, so as to watch the display means 4, the possibility of an accident increases. Accordingly, the driver 30 must watch the display means 4 as rapidly as possible so as to shorten the time for him or her to avert his or her eyes. Accordingly, because the angle of view of the human eye in a vertical direction is narrow, an increase in the sight line moving angle 33 gives a mental tension to the driver 30 and increases a psychological burden of the driver, which contributes to the fatigue of the driver 30.
Therefore, the configuration of the position, angle, display content and display screen of the display means of the conventional display device is not satisfactory in terms of alleviation of the fatigue.
As Japanese Patent Laid-Open Publication No. 2002-166748 is related to a method in which a display region for the entire display screen is changed depending on the forward and rearward position of a seat where the driver sits, or to the height of the driver's eyes, so as to allow the display region to be displayed in a size of the screen which can be easily watched by the driver. However, it remains that the position of the entire display screen is not changed, but a separate small display portion is formed at an upper portion of the screen.
Japanese Patent Laid-Open Publication Nos. 1-123731 and 5-147456 are related to methods in which the display content of a display unit mounted at a dashboard is reflected from a reflecting lens installed at an upper portion of the dashboard to create a virtual image so as to reduce the movement of the driver's line of sight, suitably by means of a head-up display (HUD) which is configured to project the virtual image onto a front windshield glass to allow the virtual image to be located ahead of the driver's eyes while being overlapped with views of the front of the vehicle. Accordingly, the projected virtual image is displayed on the front windshield glass while being overlapped with the front views of the vehicle, which makes it difficult for the driver to discern the virtual image.
Moreover, if a semi-transmission type liquid crystal is used for performing a display function by reflection of external light, transmittance of a backlight is suitably low, thereby resulting in a degradation in color reproducibility as compared to the transmission type liquid crystal. Accordingly, the above problem still occurs although a special film is attached to a panel.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgment or any form of suggestion that this information forms the prior art that is already known to a person skilled in that art.